Control system



March 28 1961 H. J. LETTINE ET AL 2,977,463

CONTROL SYSTEM Filed March 21, 1957 2 Sheets-Sheet 1 7PM/VS f7/1? March28, 1961 H J, LETTINE ET AL 2,977,463

CONTROL SYSTEM 2 Sheets-Sheet 2 Filed March 2l, 1957 IN VEN TORS./ewr//a/w/ f77/Ms UnitedStates Patenti() CONTROL SYSTEM Howard J.'Lettino andvAnthony Lettine, both of 62 Berkley St., Valley Stream,N.Y.

Filed Mar. 21, 19'57, Ser. No. 647,625 n i Claims. (Cl. Z50-2) Thepresent invention relates to a control system. More particularly, thepresent invention relates to a control system for remotely controllingan air-borne missile.

It is an object of the present invention to provide a new and improvedcontrol system.

A second object of the present invention is to provide a new andimproved control system for remotely controlling an air-borne missile.

Another object of the present invention is to provide a new and improvedcontrol system having at least one transmitting station and at least onereceiving station.

With the above objects in View, the present invention mainiy consists ofa control system including at least one transmitting station havingmeans for generating and transmitting a carrier frequency, means formodulating the carrier frequency at a predetermined modulationfrequency, the transmitting station also including means for varying thepredetermined modulationv frequency in a desired manner, and at leastone receiving station remotely located from the transmitting station andhaving receiving and demodulating means for receiving and demodulatingthe transmitting modulated carrier frequency wave to obtain a wave atthe modulated frequency, the receiving station including controlactuating means responsive to the modulation frequency wave foractuating controls at the receiving station in accordance with thedemodulated frequency wave.

In a preferred embodiment of the present invention, the receivingstation /is located on an air-borne missile and the controls, actuatedby the control actuating means, are the elevator and the rudder of themissile to control the flight of the air-borne missile.

In the present invention the means for varying the modulation frequencyare preferably constructed in the form of a joystick, simulating anactual joystick` used in an airplane.

The novel features which are considered as characteristic for theinvention are set forth in particularin the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich- Fig. 1 is an electrical schematic diagram of the modulationfrequency determining apparatus at the transmitting station;

Fig. 2 is an electrical schematic diagram showing the control actuatingmeans at the receiving station responsive to the modulation frequencywave; f i

Fig. 3 is an elevational view of the manually operated control means atthe receiving station;

Fig. 4 is a front elevational view ofthe apparatus shown in Fig. 3,-

Fig. 5 is a front elevational view of a roll control arrangement for thereceiving station; and

Fig. 6 is a side elevational view of the apparatus illusf trated in Fig.5.

Referring to the drawings and more particularly to Fig.V 1, it can beseen that the transmitting station includes a transmitter 20 having anoutput terminal connected to an antenna 21 for transmitting a carrierfrequency wave. The transmitter 20, shown only in block form, can be aconventional transmitter, -the carrier frequency outputV of which isadapted to be keyed by modulating means.

Connected to the input of thentransmitter 20 is a conductor 22, theother end of which is connected to a fixed contact 8 of a relay 10having a relay winding 11 and three other fixed contacts 4, 5 and 9respectively.

The relay 1t) valso includes two movable armatures 6 and 7 which areshown respectively connected to the fixed contacts 4 and 5. In Fig. 1,the unenergized condition of the relay 1t) is illustrated. In theenergized condition, the movable armatures 6 and 7 are respectivelymoved into engagement with the fixed contacts 8 and 9 instead of 4 and5.

The armature 6 is connected by a conductor i12 to the electrical groundand the armature 7 is connected by a conductor 13 to Vone side of amotor 30, the other side of which isfconnected to the fixed contact of aswitch 31. The ymovable contact of the switch 31 is connected to ajunction point 32 which is respectively connectedv to the positiveterminal of a direct current source 33 and to the negative terminal of adirect current source 34.

The positive terminal of the source 34 is connected to the fixed Contact9 of the relay 10 while the negative terminal of the source 33 isconnected to the electrical ground. v

The fixedpcontact 5 is connected bya conductor 35 to one end of avariable resistor 36, the other end of which is connected to theelectrical ground.

Connected across the winding 1.1 of the relay 10 is a capacitor 37having one plate thereof connected by a conductor 38 to the fixedcontact 4 and by a conductor 39 to the movable arm `41 of apotentiometer 4d.

The potentiometer 40 has an upper end point 1 connected to theelectrical ground and a lower end point 3 connected to the other plateof the capacitor` 37 and also connected to one end of a resistor 42..The other end of resistor 42 is connected to the fixed contact of aswitch 43, the movable contact of which is connected to a source B+ ofoperating potential.

The purpose of the apparatus shown in Fig. 1 is to generate desiredmodulating frequencies for keying the transmitter 20 so as to modulatethe carrier frequency wave output of this ,transmitter in Va desiredmanner to control the control actuating means in the remote receiverstation.

In operation, when the switch 43 andy is closed and the switch 31, 32 isopen, the relay winding 11 of relay 10 has a potential applied theretodepending on the voltage divider arrangement made up of the resistors 42and the potentiometer 40 and the position of the movable arm l411 of thepotentiometer 4t). If the potential applied across the relay winding 11is sufficient to energize the same, the armatures 6 and 7 will be' movedout of contact with the fixed contacts 4 and 5 and respectively intocontact with the fixed contacts 8 and 9.

When the armature 6 is attracted to the fixedA contact Patented Mai. 2s,1961 across the relay winding 11 due to the B+ source will be decreased.However, due to the action of the capacitor 37, this voltage will notimmediately drop to zero. The

relay winding 11 will accordingly remain energized for a.

returned to their initial unenergized position by restoring means, notillustrated. It is clear that the restoring means may be springs forexample.

As soon as the armature 6 again contacts the fixed contact 4, the upperportion of the potentiometer 40 between the movable arm 4 and the endpoint 1 will again be short circuited to increase the portion of thepotential applied across the relay winding 11. This again energizes therelay winding 11 and the movable armatures 6 and 7 return into contactwith the fixed contacts 8 and 9.

The'above described cycle is repeated at a repetition rate dependingupon the position of the movable tap 41 of the potentiometer 40. Themodulation frequency can be varied between two extreme positions 1 and 3of the potentiometer 40 by means of the tap 41 thereof. That is, if thepotentiometer tap 41 is moved to the point 1 so that the tap issubstantially connected to the electrical ground, the relay winding 11will become energized as soon as the switch 43 is closed and will remainin energized condition. Therefore, the electrical ground potential willbe continuously applied to the conductor 22 to provide a constantvoltage superimposition for the carrier frequency wave output of thetransmitter 20.

Conversely, if the potentiometer tap 41 is moved towards the end point 3of the potentiometer 40, the relay winding 11 and the capacitor 37 willbe substantially short circuited so that the relay Winding 11 will notbe energized regardless of the position of the switch 43 and accordinglyno modulation will be applied to the carrier frequency output of thetransmitter 20.

It is therefore seen that by manually controlling the position of thetap 41 of the potentiometer 40, it is possible to vary the modulationfrequency for the transmitted carrier frequency wave.

Automatic control means are also provided in the embodiment illustratedin Fig. 1. These control means include the motor 30, the shaft of whichis connected to the winding of the potentiometer 40 so as to rotate theentire potentiometer winding with respect to the movable tap 41 thereof,regardless of any set position of the tap 41, in a direction determinedby the direction of rotation of the shaft of the motor 30. It can beseen that when the switch 31 is closed, and the relay 10 is energized bythe direct current source B+, the movable armature 7 moves back andforth in synchronism with the movable armature 6 as described above.

When the armature 7 is in contact with the fixed contact 9, the motor 30is energized by the direct current source 34 and the shaft thereof isrotated in a direction determined by the polarity of the source 34. Whenthe armature 7 is in contact with the fixed contact 5, the motor 30 isenergized by the direct current source 33 and is rotated in the oppositedirection since the polarity of the direct current source 33 is oppositeto the polarity of the direct current source 34. In the unenergizedcondition of the relay winding 11, the motor 30 is connected in serieswith the variable resistor 36 for reasons which will be explainedhereinafter.

When the relay winding is in energized condition and the armature 7 isconnected to the fixed contact 9, the motor 30 is rotated by the source34 in a direction so that the end point 3 of the potentiometer 40 isbrought 4 closer to the tap 41 thereof. This tends to tie-energize therelay winding 11 more quickly. On the other hand when the relay windingis in unenergized condition, the armature 7 making contact with thefixed contact 5 causes the source 33 to rotate the motor 30 in thereverse direction so that the end point 1 of the potentiometer 40 isdriven toward the tap 41. This serves to end the deenergized period ofthe relay winding 11 more quickly.

Accordingly, the action of the motor 30 serves to oscillate the windingof the potentiometer 40 back and forth quickly so that the tap 41 iseffectively maintained at the central position 2 of the potentiometer40, if so set manually before, and the energization and de-energizationperiods for the relay winding 11 are substantially equal. With thiscondition, the carrier frequency wave is in modulated and in nnmodulatedcondition for approximately equal time periods. The purpose of thisarrangement will be described hereinbelow with respect to the receivercontrols.

Referring now to Fig. 2, the receiving station includes receiving anddemodulating means 50 which is connected to an antenna 51 for receivingand demodulating the carrier frequency waves received by the antenna 51and transmitted from the antenna 21. Due to the' action of the receiverand demodulator, there appears on the output conductor 52 ofthedemodulating means 50, a wave which corresponds to the modulationfrequency wave used to modulate the carrier frequency wave at thetransmitter station.

This modulation frequency wave is applied tothe relay winding 53 of arelay 60 which has connected thereacross a capacitor 54. The oppositeend of the relay winding 53 is connected to a source of operatingpotential B+. The relay winding 53 is accordingly energized andde-energized in synchronism with the modulation frequency appearing onthe conductor 52.

The relay has two movable armatures 61 and 62 which in the de-energizedcondition of the relay can make Contact with the fixed contacts 63 and64 respectively. In the energized condition of the relay 60, thearmatures 61 and 62 make respective contact with the fixed contacts 66and 67.

The armature 61 is connected on a conductor 68 to one side of a motor70, the other side of which is connected by a conductor 69 to thearmature 62. It can be seen that when the armatures 61 and 62 are in theillustrated position, the motor 70 is energized by the direct currentsource 71 and is rotated in a direction determined by the polarity ofthis source 71.

When the relay 60 is energized, the armatures 61 and 62 are respectivelyconnected to the contacts 66 and 67 to connect the source 71 to themotor with reversed polartiy so that the motor 70 is rotated in theopposite direction. That is, it can be seen that the fixed contacts ofthe relay 60 are connected in the manner of the reversing switch.

The motor 70 is connected to a worm 72 which in turn is meshed with theworm gear 73 having fixedly connected thereto a threaded rod 74.Threaded on the rod 74 is an internally threaded bushing 76 which isadapted to move along the rod 74 in a direction determined by thedirection of rotation of the rod 74.

When the receiving station is connected for the purpose of controllingan air-borne missile, the arrangement shown in Fig. 2 is mounted on theair-borne missile and the bushing 76 is connected by a lever 77 to thecontrol surface 78 at the pivot point 79. The control surface can be therudder or the elevator of the missile, for example.

Accordingly, in operation, the relay 60 will be energized andde-energized for respective time periods depending upon the modulationfrequency determined at the transmitter. If the energization andde-energization time periods for the relay 60 are equal, it can be seenthat the control surface 78 will be moved back and germes forthprecisely the same amount so that the missilebeing guided by the controlsurface will continue in its fixed direction. Actually, it is to beappreciated that the'energization and the de-energization of the motor70 is for such short time periods that for all practical purposes, thecontrol surface 78 is held ina fixed position.

However, if it is desired to move the control surface in such a mannerso as to change the direction of the missile, the tap 41, of Fig. 1 ofthe potentiometer 401 is moved in a direction to increase either theenergization or the de-energization time period. That is, if themodulation frequency as received in the receiver of Fig. 2 is such thatthe relay 6()v is energized for time periods longer than the`de-energization periods thereof, itis clear that the motor 70 will'move the control surface 78 a greater amount in oneV direction, duringthe energization of the relay 60, than in the other direction,yduring'the de-energization thereof. Accordingly, the resultant directionof the control surface 78A will be changed in a predetermined mannerdepending on the direction of the change and the amount thereof.

If, in the transmitter of Fig. 1, the switch 31 is open so that theautomatic servo feedback mechanism provided by the motor 30 is not used,the change in direction is `provided by moving the tap 41 manuallytoward the end point 1 or the end point 3 depending on which change ofdirection is desired for the air-borne missile. When the missile haschanged its direction the proper amount and it is desired to maintainthis missile in the new xed direction, the manually operated tap 41 ismerely moved back to the central position 2 so that the energization andde-energization time periods are again substantially equal.

If the automatic follow mechanism provided by the motor 30 is to beused, the tap 41 is merely moved to either end position depending on thedesired direction of change and the motor 30, upon closure of the switch31 will move the entire winding of the potentiometer with respect to theset position of the tap 41 so that the tap 41 will again be positionedback opposite the central point 2 of the winding.

It should be appreciated that in the transmitting station, two separatemodulating frequency controls can be provided if two different controlsurfaces on the air-borne missile have to be controlled. That is, onemodulation frequency arrangement would be used for the rudder of theair-borne missile, for example and the other for the elevator thereof.In the receiving station, tuned circuits may be provided, the output ofone of the tuned circuits being connected to the control circuit for therudder and the other to the control circuit for the elevator. Themodulation frequency for the rudder will therefore only control therudder and the modulation frequency for the elevator will therefore beused only for the control of the elevator.

Referring now to Figs. 3 and 4, an arrangement will be described whereina single manual element can be used for simultaneously controlling therudder and elevator control signals at the transmitter station by usingtwo separate modulation devices. dn Figs. 3 and 4, a support member 81can be seen on which is rotatably mounted, at the upper portion thereof,`a shaft 82. Fixedly connected to the shaft 82 is a spur gear 83 whichis meshed with a second gear 84. The gear 84 is fixedly connected to therotatable shaft of a potentiometer 86 which is equivalent to the type ofpotentiometer shown in Fig. l, namely the potentiometer 40.

The housing of the potentiometer 86 is fixedly connected to a gear 87which is meshed with a worm gear 88 fixedly connected to the shaft of amotor 89.

It can be seen that the movable shaft of the potentiometer 86 can beadjusted by rotation of the shaft 82, thereby rotating the gear 83 andthe gear 84 while the housing of the potentiometer 86 is maintained infixed position by the gear 87 being at standstill.

. 6 When the motor `89 vis energized, theworm 88 corinected theretorotates the gear 87 rto thereby rotate the housing of the potentiometer86 while the tap or shaft of the potentiometer 86 is held in xedposition by the gear 84 being at standstill.y

As can best be seen in Fig. 4, a pin 91 is connected to the shaft 82 atone of its ends and at the other of its ends is connected to a gear '92.The gear 92 has `a manually operable handle 93 for varying the positionthereof about the pin 91. The gear 92 meshed: with a gear 94 which isconnected to the shaft 41 of the potentiometer 40. 'The housing ofpotentiometer 40 is fixedly connected to a gear 95 which is meshed witha worm 96 fixedly connected to the 'shaft of the motor `30 .s0 as torotate therewith. v

It can be seen that in operation, the handle 93 can be used to rotatethe shaft 82 in direction of arrows'A to control the movable tap on thepotentiometer 86 and also in direction of arrows C to rotatethe shaft 41to control the position of the tap 41 on the potentiometer 40.

As is shown, the shaft 82 carries a bracket 82 in which the pin 91 ismounted, similarly a second pin 41 as mentioned above. In addition, agear S3 is attached to the shaft 82 in transverse direction so asto meshwith a smaller gear 84 rotatably supported` in a portion 81' of theframe or housing 81. The shaft of the gear 84 is at the same time thetap carrying shaft of the potentiometer 86. The winding and housing of`this potentiometer 86 is attached to a worm gear 87 which meshesV with aworm 88 driven by a motor 89. Thus, when the 'handle 93 is swung in,direction of arrows A the movable tap of the potentiometer 86 is movedalong its winding,

while independently the potentiometer winding may be:

rotated by the action of motor 89.

It will be understood that the potentiometer 86, and its movable tapfunction exactly like the potentiometer 40 and its movable tap 41 andconstitute the control elements of a circuit arrangement analogous tothat of Fig. 1-.

It is clearthat the arrangement shown in Figs. 3 and 4 is similar to ajoystick which is used for controlling the rudder and elevator controlsof an airplane. Therefore,

an operator can move the handle 93 from side to side in .5

one plane to control one of the control surfaces and move the handle 93back and forth in a plane transverse thereto to control the other of thecontrol surfaces.V v It)v is clear that the handle 93 can be moved toany ofthe intermediate positions to provide simultaneous control f for-both the rudder and control of the remote air-bo missile.

Therefore, with the present invention, it can be seeny that an operatorcan manually position the movable taps of the potentiometers 40 and 86in the transmitterI circuit for supplying the proper modulationfrequenciesforV the.

carrier frequency waves transmitted by the transmitter antenna 21. Inthe receiver, the control surfaces are properly positioned by controlsurface actua-tingnien'r-l with the received f lbers which are moved inaccordance modulation frequency waves.

The potentiometer 36, Fig. l, is used to compensate for creeping of therudder or elevator of the missile beingV guided. This compensates forany time delay introduced.y v by the relay operation in the receiverwhen the sameis;` energized less than it is de-energized so that themovement of the motor 30 in the missile will be longer in one directionof rotation than in the other. Since lthe p0.- ten-tiometer 36 is inseries with the motor 30 itis clear that the motor 3i) will turn thepotentiometer 40 at a `slow worm gear and differential gear arrangement.

thereby providing proper stabilizing control for-the missile.

A motor connected in circuit with the potentiometer 114 is connected toa pair of control surfaces through a When the missile is level, the tapconnected to the potentiometer arm 112 is in the center position,sending equal posi-l tive and negative pulses to the motor, causing thecontrol surfaces to stand still. When the missile rolls, the pendulum orgyroscope moves the potentiometer arm 112, making one pulse longer thanthe other (depending on the direction of the roll) causing the motor torotate,

`moving the control surfaces in opposite directions to correct the roll.

If a closed servo loop system is desired, another small motor isconnected in parallel to the control surface motor and attached to thepotentiometer case 113, the same as the follower motors in thetransmitter control box.

Another method of obtaining a closed servo loop would be to mount thepotentiometer case on the differential gear arrangement.

The advantage of this system is that it eliminates dead space, becauseit corrects instantly.

This system can also be used as -an automatic pilot, when thepotentiometer is attached to a gyroscope indicating direction.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofcontrol systems differing from the types described above.

While the invention has been illustrated and desc-ribed as embodied inapparatus for remotely controlling airborne missiles, it is not intendedto be limited -to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully lreveal the gistof the present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specic aspects of this invention and,therefore, such adaptations should and are intended to be comprehendedwithin the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a transmitter having modulating means, in combination, energizingmeans for energizing the transmitter modulating means, switch meansconnected in circuit between said energizing means and the modulatingmeans and movable between a circuit closing position wherein themodulating means is energized and a circuit opening position wherein themodulating means is de-energized,

electromagnetic means for moving said switch means between its circuitopening and closing positions, and frequency determining means connectedto said electromagnetic means for controlling the frequency at whichsaid electromagnetic means moves said switch means between its circuitopening and circuit closing positions,

said frequency determining means including a capacitor connected inparallel with said electromagnetic means, and a potentiometer connectedin circuit with said capacitor,

`said potentiometer having a variable resistance which in Vquencydetermining means includes a capacitor connected in parallel with saidelectromagnetic means, and a potentiometer connected in circuit withsaid capacitor,

lsaid potentiometer having a variable resistance which in .combinationwith the capacitance of said capacitor determines the frequency ofoperation of said electromagnetic means.

3. Apparatus as claimed in claim 1 wherein movin means are connected tosaid potentiometer for varying the resistance thereof in oppositedirections respectively, in each of said switch positions.

4. Apparatus as claimed in claim 3 wherein said moving means includes amotor having a rotatable shaft connected to the housing of saidpotentiometer, a second energizing means connected in circuit with saidmotor in one of said switch positions for rotating said motor in a rstdirection and a third energizing means connected in circuit with saidmotor in the other of said positions for rotating said motor in thedirection opposite to said first direction.

5. Apparatus as claimed in claim 3 wherein said moving means includes asupport member and an elongated member rotatably mounted on said supportmember, a shaft mounted on said elongated member, substantiallytransverse thereto and rotatable with respect to said elongated member,at least one motor mounted on said support means and having a rotatableshaft, rst coupling means for coupling said rotatable shaft to saidpotentiometer for rotating the same in a direction depending upon thedirection of rotation of said rotatable shaft of said motor, and secondcoupling means connecting the movable tap of said potentiometer to saidelongated member, whereby when said elongated member is rotated, theshaft of said potentiometer is rotated by said second coupling meanswhile said potentiometer is prevented from rotating, and when said motoris energized, the rotatable shaft thereof rotates said potentiometerwhile the `potentiometer shaft is prevented from rotating.

References Cited in the tile of this patent UNITED STATES PATENTSGebhard Oct. 25, 1932 Gebhard Ian. 24, 1933 OTHER REFERENCES

